1. Field of the Invention
The present invention relates to devices for loading and unloading containers and more particularly, to a chain loading mechanism for safely loading a movable frame onto a stationary vehicle.
2. Description of Related Art
A conventional cab and chassis vehicle when used to transport loads usually comprises a frame and a device for pulling a movable frame from the ground up and over onto the vehicles' stationary frame, and guiding the frame into the loaded position. During normal usage, the movable frame supports a load which is transferred from the ground to the vehicle chassis via an arrangement of elevating booms and guide systems that are controlled by an operator. This simple approach has many limitations and there are many patents disclosing devices that simplify the procedure and/or improve the safety aspects of such a maneuver.
U.S. Pat. No. 1,794,318 (Perkins et al.) discloses a dumping body frame truck that is driven by a chain drive. The body is formed by telescopic sections that are collapsed to dump a load. While the sections are designed to slide along the chassis body, there is no bed that is removable from the chassis.
U.S. Pat. No. 2,811,269 (Anderson) discloses a removable bed that relies on a winch assembly to draw the truck body onto the chassis.
U.S. Pat. No. 5,203,788 (Marmur) discloses an apparatus for loading a container onto a truck body or trailer. This arrangement discloses the use of a pivoting arm and a cable to move the trailer.
U.S. Pat. No. 5,269,746 (Zoromski) discloses a container loading and unloading system that is particularly suited for loading campers and cargo boxes onto a truck bed. The system appears to be independent of the vehicle except for a yoke and pivot bar structure that is attached to the rear bumper.
U.S. Pat. No. 5,856,869 (Slokum et al.) discloses a removable load bed that includes a tiltable bed that is operated by a piston to control loading and unloading of the container. The system relies on a cable and bracket system to move the container. While the tiltable bed and interlocking bracket and cavity aspect of this patent appear to address deficiencies that are present in the previously described patents, it still suffers from the potential that the cable may come off the bracket, and therefore, could potentially be a safety hazard.
The frames of common conventional loading devices are generally similar in size and construction, and thus many of the loads that are to be used with such a frame arrangement tend to rely on a smooth and easy transfer from the ground to the truck bed. It is often difficult to maintain adequate control of this maneuver, and thus inadvertent lateral movement and slippage of the pulling mechanism can occur, especially during the initial lifting procedure.
Thus, there is a need for a removable load bed assembly for use with a conventional cab and chassis vehicle that provides a safe method of transferring a load from the ground onto the chassis of the vehicle. This patent should not be limited to this only. Other examples are military track and rubber tired vehicles that could have the bodies changed from a gun carrier to personal carrier to an ambulance body. This system will lift any load from one level to another.